The present invention relates to drip irrigation apparatus, and particularly to such apparatus effective to regulate the flow of the water therefrom in response to changes in the water supply pressure.
One known construction of apparatus of this type includes a drip irrigation unit for insertion into a water supply pipe to reduce the flow through an outlet opening in the water supply pipe, comprising: a cylindrical member having an outer diameter substantially equal to the inner diameter of the water supply pipe and fixed therein with the outer face of the cylindrical member in contact with the inner face of the water supply pipe; the cylindrical member being formed with an inlet opening therethrough from its inner face to its outer face for conducting the water from the interior of the water supply supply pipe to the outer face of the cylindrical member, an outlet cavity in the outer face of the cylindrical member alignable with the outlet opening in the water supply pipe, and a regulated flow-reducing pathway between the inlet opening and outlet cavity.
Examples of apparatus of this type of known construction are illustrated in U.S. Pat. No. 4,519,543, and U.S. Pat. No. 4,687,143. In these known constructions, the cylindrical member is of rigid plastic material and includes a flexible membrane or the like to produce the regulation in response to changes in the water supply pressure. Since such constructions involve a multiplicity of parts, they are relatively expensive to produce and to assemble into the water supply pipe.
U.S. Pat. No. 4,824,025 discloses a drip irrigation unit constituted of a cylindrical member made of a deformable elastomeric material in which the flow regulating means is a deformable tubular member diametrically traversing the cylinder, the tubular member being deformable by the fluid pressure in the conduit line to restrict the flow of fluid therethrough. In such a drip irrigation unit, however, the diametrically traversing tubular member also interferes with the flow of the water through the line, and thereby produces a pressure loss in the water flowing through the line.